THE HYDROLOGY OF THE NILE RIVER BASIN: LITERATURE REVIEW AND COMPARISON BETWEEN TWO MODEL STRUCTURES

Abstract.

This report presents a review for some of the hydrological studies that were carried out in the Nile Basin. Firstly, the studies concerned with the understanding of the hydrological process are discussed, to show the gap between the physical understanding and the modeling of the hydrological processes in the Nile basin then to discuss some of the studies carried out to bridge this gap. Secondly, two main research concerns in the Nile basin are discussed; showing the effects of watershed characteristics changes and climate changes on the hydrological processes in the Nile basin. Lastly, a comparison between two modeling approaches is introduced the results show that despite that the two models are different in structure, both give very close results.

1 Introduction

Water is the source of life on earth. Sustainable water use and management are of paramount importance to maintain a healthy life for all creatures. Hydrology is considered a very important tool that assists the implementation of proper management that benefits industry, agriculture, and the environment. The study of hydrology is a difficult task because it requires the observation and understanding of diverse and complex processes that govern the water cycle on earth. For centuries, there was big effort done to study, model and represent hydrological processes over and under the ground. Nevertheless, the hydrological phenomenon is not fully understood and still needs more and more studies to overcome the issues and the shortage of understanding.

The Nile River is one of the most important rivers in the world. The basin is home for 257 million people that are almost 20% of African population (Nile Basin Initiative, 2016), moreover, the Nile basin is characterized by one of the most important biodiverse ecosystems on earth. The studying of the river hydrology is of high importance for many aspects. First, the high vulnerability of the basin to floods and droughts which pose risk for the lives of population especially those living in flood plains. Second, there are political disputes between upstream and downstream countries over the use of water which is basically water management problem that needs to be supported by hydrological studies. Third, the system is suffering from great losses due to evaporation and seepages along the river course which needs further studies and to be prevented if possible. The system is subjected to high erosion especially in the Blue Nile basin which is a very important issue. Lastly, the basin hydrology is affected by the changes in basin characteristics due to deforestation and changing land uses, also due to climate change. All these points and more are of high concern to the hydrological research in the Nile basin.

This report aims to provide a literature review for selected studies in the Nile Basin that draw much attention in last years. The topics covered are; the hydrological modeling used  in the basin studies and the effort done to improve them, the detection of hydrological changes due to the change of watershed characteristics, and the expected effects of climate change on the hydrology of the basin. In addition to literature, the final part of the report will include research work done to compare between two different model structures by using the area of Upper Blue Nile as a case study.

The following structure is followed in this report. Section (2) covers background information about the study area of the Nile River.  Then, Section (3) discusses the literature for three different issues that were the main focus of the hydrological studies that carried out in the Nile basin. First, the effort made to improve the understanding of the hydrological process and to link the physical understanding to modeling is covered. Second, the last section of the literature will discuss two of the main areas that draw much attention in the Nile basin: the studies of watershed changes and their effects on the hydrological process, and the climate change studies. Section (4) discusses the modeling work done. Finally, section (5) will include the conclusions for the literature and the modeling work results.

2 Study Area